Chlorosulfonated Polyethylene Synthesis Essay

A product of the chemical modification of polyethylene by chlorine and sulfur dioxide, chlorosulfonated polyethylene has a density of 1.11–1.26 g/cm3, a chlorine content of 27–45 percent, and a sulfur content of 0.8–2.2 percent. Owing to the presence of chlorine, it is resistant to fire, oil, and the action of microorganisms and exhibits good adhesion to various surfaces. It is insoluble in aliphatic hydrocarbons and alcohols, slightly soluble in ketones and esters, and readily soluble in aromatic hydrocarbons, such as toluene and xylene, and in chlorinated hydrocarbons.

Chlorosulfonated polyethylene is superior to other rubbers in its resistance to the effects of ozone and inorganic acids, such as chromic, nitric, sulfuric, and phosphoric acids, as well as to the effects of concentrated alkalies, chlorine dioxide, and hydrogen peroxide. It is resistant to light, is impermeable to gas, and has good dielectric properties. The —SO2Cl groups and labile chlorine atoms participate in the vulcanization of chlorosulfonated polyethylene; a typical vulcanizing system consists of MgO, 2-mercaptobenzothiazole, diphenylguanidine, and rosin. The tensile strength of pure rubbers made of chlorosulfonated polyethylene may reach 32 meganewtons/m2 (320 kilograms-force/cm2), with a relative elongation of 350–600 percent. Such rubbers have high resistance to wear and repeated deformation. The temperature range for their most efficient use is –60° to 180°C. Chlorosulfonated polyethylene made from high-density polyethylene may also be used in unvulcanized form.

Chlorosulfonated polyethylene is used in the production of industrial and household goods and of anticorrosion coatings to be applied by the rubberizing method. It is used for insulating various cables, including ship cables. It is also used as a film-forming agent in varnishes and paints for the preservation of wood, metal, and reinforced concrete and as a base for adhesives and hermetic sealants.

The trade names of chlorosulfonated polyethylene are KhSPE in the USSR and Hypalon in the USA. In 1976, world production amounted to about 30,000 tons.

REFERENCE

Entsiklopediia polimerov, vol. 3. Moscow, 1977.

G. M. RONKIN

OVERVIEW

Best known by the trade name Hypalon®, chlorosulfonated polyethylenes are valued for their attractive combination of physical resilience and chemical resistance to corrosives, heat, oil, oxygen, ozone, and weather. Both heat resistance and low temperature flexibility can be enhanced through the use of lower amounts of chlorine, but oil resistance is only fair in such formulations. Higher chlorine levels lead to greater oil resistance at the expense of heat resistance and low temperature flexibility. CSM can also be compounded to retain permanent bright colors. On the downside, CSM suffers from poor compression set resistance.